Bring Sphinx pipeline current #57
Description
Netlify officially announced support for Python versions newer than 3.8 today. It's nice that they finally got around to it, because Python 3.8 is EOL as of earlier this month.
Sopel should build its docs on a more current version of Python, probably 3.11 or 3.12 for now. Preview docs built directly from sopel-irc/sopel@master should also be moved to the same version, for validation as we continue working on the docs upstream.